Header Format Issue

When I view my blog, http://home-decorating-ideas.org, in IE browser, the bottom of the header gets cut off. When I view it in Firefox, there’s a big gap between the header and the menu bar. I’d like to get it right for both.

My efforts to fix so far have focused on trying different size headers (no help), to mucking about in the header.css in Theme Editor. There, I have adjusted the padding from 0 to 25px in this line: padding:10px 20px 25px. It’s helping but there must be a good solution other than this. Anybody know? Thanks.